Humanitys impact is threatening nearly 50 billion years of
evolutionary history: study
Human activities threaten to saw off branches of the tree of life
putting irreplaceable species at risk of extinction.
So finds a study published Tuesday in the journal Nature
Communications which highlights the need for urgent conservation
actions.
Barring such action, the researchers wrote, close to 50 billion
years of evolutionary history worldwide is at risk.
Scientists from Imperial College London and the Zoological Society of
London (ZSL) began their research by first analyzing the worlds
reptiles and then terrestrial vertebrates like amphibians, birds, and
mammals, looking at how areas with a high human footprintincluding
factors like deforestation and population densitycoincide with areas
containing species with unique evolutionary history, or branches on
the tree of life.
The scientists found a troubling overlap, with areas in the Caribbean,
the Western Ghats of India, and large parts of Southeast Asia singled
out as experiencing both extreme human pressures and unique
biodiversity.
The greatest losses of evolutionary history will be driven by the
extinction of entire groups of closely-related species that share long
branches of the tree of life, such as pangolins and tapirs, and also
by the loss of highly evolutionarily distinct species that sit alone
at the ends of extremely long branches, such as the ancient Chinese
crocodile lizard (Shinisaurus crocodilurus), the Shoebill (Balaeniceps
rex), a gigantic bird that stalks the wetlands of Africa, and the Aye-
aye (Daubentonia madagascariensis), a nocturnal lemur with large
yellow eyes and long spindly fingers.
At risk with the possible extinctions is not just the intrinsic value
of the threatened species in and of themselves but their roles in the
greater web of life. From BBC News:
Many [of the at-risk animals] carry out vital functions in the
habitats in which they live. For example, tapirs in the Amazon
disperse seeds in their droppings that can help regenerate the
rainforest. And pangolins, which are specialist eaters of ants and
insects, play an essential role in balancing the food web.
Lead author Rikki Gumbs of ZSLs EDGE of Existence program and the
Science and Solutions for a Changing Planet Doctoral Training
Partnership at Imperial College London put the findings in stark
terms.
Our analyses reveal the incomprehensible scale of the losses we face
if we dont work harder to save global biodiversity, said Gumbs. To
put some of the numbers into perspective, reptiles alone stand to lose
at least 13 billion years of unique evolutionary history, roughly the
same number of years as have passed since the beginning of the entire
universe.
Our findings highlight the importance of acting urgently to conserve
these extraordinary species and the remaining habitat that they occupy
in the face of intense human pressures, said co-author James
Rosindell of Imperial College London.
In blog post for ZSLs EDGE of Existence program,
Gumbs highlighted the scope of the problem.
We are still learning the true extent to which human activities are
encroaching on our natural habitats and threatening our most unique
and important biodiversity. Our findings indicate that the magnitude
of our impact as a species on the natural world is incomprehensibly
large, and appears to be overwhelmingly impacting the most
irreplaceable areas and species on the planet, he wrote.
"https://www.alternet.org/2020/05/humanitys-impact-is-threatening-
nearly-50-billion-years-of-evolutionary-history-study/"

Study shows erosion of ozone layer responsible for mass extinction
event
Researchers at the University of Southampton have shown that an
extinction event 360 million years ago, that killed much of the
Earth's plant and freshwater aquatic life, was caused by a brief
breakdown of the ozone layer that shields the Earth from damaging
ultraviolet (UV) radiation. This is a newly discovered extinction
mechanism with profound implications for our warming world today.
The ozone collapse occurred as the climate rapidly warmed following an
intense ice age and the researchers suggest that the Earth today could
reach comparable temperatures, possibly triggering a similar event.
Their findings are published in the journal Science Advances.
Following melting of the ice sheets, the climate was very warm, with
the increased heat above continents pushing more naturally generated
ozone destroying chemicals into the upper atmosphere. This let in high
levels of UV-B radiation for several thousand years.
Lead researcher Professor John Marshall, of the University of
Southampton's School of Ocean and Earth Science, who is a National
Geographic Explorer, comments: "Our ozone shield vanished for a short
time in this ancient period, coinciding with a brief and quick warming
of the Earth. Our ozone layer is naturally in a state of flux
constantly being created and lostand we have shown this happened in
the past too, without a catalyst such as a continental scale volcanic
eruption."
Professor Marshall says his team's findings have startling
implications for life on Earth today: "Current estimates suggest we
will reach similar global temperatures to those of 360 million years
ago, with the possibility that a similar collapse of the ozone layer
could occur again, exposing surface and shallow sea life to deadly
radiation. This would move us from the current state of climate
change, to a climate emergency."
"https://phys.org/news/2020-05-erosion-ozone-layer-responsible-
mass.html?utm_source=nwletter&utm_medium=email&utm_campaign=weekly-
nwletter"